TOKYO Oct. 18, 2013. Radioactive material density (total beta) increased in groundwater taken from an observation hole near the tank from which contaminated water had previously leaked at Fukushima Daiichi Nuclear Power Station, after typhoon No.26 (Wipha) passed through, TEPCO announced today. No density increase was observed in nearby seawater.

The density increase was observed at observation hole E-1, located approx. 20 meters to the north of the leaked tank at the H4 tank area. 400,000 Bq/L of total beta, which is the total of radioactive materials which emit beta rays, including strontium 90, was detected in the sampling water taken on October 17. The density of the water taken the day before was 61 Bq/L. Cesium134 and cesium137 was not detected from the water. The leak from the tank had been found on August 19, and prompt measures have been taken since then, such as transferring the water from the tank and removing the surrounding soil. No new leak has been observed at nearby tanks.

Judging from these facts, the company is assuming that the cause of the density increase may be that the residual radioactive materials in the soil from this leak had moved to this area via rainfall from typhoon No.26 (Wipha). After the leakage from the tank, the company had promptly placed sandbags in the drainage paths to prevent the water from flowing out to the ocean. No density increase has been observed in nearby seawater.

TEPCO stated that it will continue monitoring at the point in question, as well as in the nearby seawater. The monitoring results are promptly reported to the regulators and announced on TEPCO's homepage every day. Please refer to the below for the monitoring results.http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/index-e.html

TEPCO, Inc. is a provider of electricity to the Kanto region, which includes Tokyo and Yokohama. The company is headquartered in Tokyo. The Fukushima Daiichi Nuclear Power Station was struck by a tsunami after an earthquake that occurred in March 2011. For more information, please go to http://www.tepco.co.jp/en/index-e.html.